Control of wood-destroying pests with thiamethoxam

ABSTRACT

There are described a method for the control of wood pests which comprises applying to the pests or to their habitat a pesticidally active amount of a pesticidal composition comprising, as active ingredient, at least a compound of formula 
                         
in free form or in the form of an agrochemically acceptable salt, and at least one adjuvant; the corresponding use of those compounds, pesticidal compositions whose active ingredient is selected from those compounds, a process for the preparation of such compositions, the use of such compositions, and plant propagation material accordingly protected against pest attack.

This application is a 371 filing of International Application No.PCT/EP01/09859, filed Aug. 27, 2001, the contents of which areincorporated herein by reference.

The invention relates to a method of controlling wood pests whichcomprises applying to the pests or to their habitat a pesticidallyactive amount of a pesticidal composition comprising, as activeingredient, at least a compound of formula

in free form or in the form of an agrochemically acceptable salt, and atleast one adjuvant; to the corresponding use of those compounds, topesticidal compositions comprising thiamethoxam as active ingredient, toa process for the preparation of such compositions, to the use of suchcompositions, and also to plant propagation material accordinglyprotected against pest attack.

The compound used according to the invention, thiamethoxam(3-(2-chloro-1,3-thiazol-5-ylmethyl)-5-methyl-1,3,5-oxadiazinan-4-ylidene(nitro)amine),is known to the person skilled in the art, for example from ThePesticide Manual, The British Crop Protection Council, Twelfth Edition,page 896.

Agrochemically acceptable salts of thiamethoxam are, for example, acidaddition salts. Those acid addition salts are formed, for example, withstrong inorganic acids, such as mineral acids, e.g. perchloric acid,sulfuric acid, nitric acid, nitrous acid, a phosphoric acid or ahydrohalic acid, with strong organic carboxylic acids, such asunsubstituted or substituted, e.g. halo-substituted,C₁-C₄alkanecarboylic acids, e.g. formic acid, acetic acid ortrifluoro-acetic acid, saturated or unsaturated dicarboxylic acids, e.g.oxalic, malonic, succinic, maleic, fumaric and phthalic acid,hydroxycarboxylic acids, e.g. ascorbic, lactic, malic, tartaric andcitric acid, or benzoic acid, or with organic sulfonic acids, such asunsubstituted or substituted, e.g. halo-substituted, C₁-C₄alkane- oraryl-sulfonic acids, e.g. methane- or p-toluene-sulfonic acid. Thecompound used according to the invention in free form and in the form ofits agrochemically acceptable salts is to be understood hereinbefore andhereinafter as including, where appropriate, the corresponding salts andthe free compound, respectively. Preference is given to thiamethoxam infree form.

Many different classes of active ingredient are mentioned in theliterature as arthropodicidally active ingredients for controllingtermites. It has now been found, surprisingly, that the compoundthiamethoxam has especially advantageous activity against wood pests,especially against termites, more especially representatives of theorder Isoptera.

Termites include especially the families Hodotermitidae, Kalotermitidae(Incisitermes), Rhinotermitidae and Termitidae. The method according tothe invention controls, especially, termites of the genera and species:Allondothermes spp., for example A. giffardi and A. tenax;Ancistrotermes, for example A. cavithorax, A. guineensis, A. latinotusand A. periphrasis; Amitermes spp., for example A. evuncifer;Cryptotermes spp., for example C. brevis and C. cavifrons; Heterotermesspp., for example H. aureus, H. indicola and H. tenuis; Hodotermes spp.,for example H. mossambicus; Macrotermes spp., for example M.michaelseni, M. falcifager, M. bellicosus, M. subhyalinus and M.natalensis; Microtermes spp., for example M. albopartitus, M.redenianus, M. lepidus, M. traghardi and M. thoracalis; Nasutitermesspp., for example N. costalis; Neotermes spp., for example N. gestroiand N. jouteli; Odontotermes spp., for example O. bruneus, O. classicus,O. smeathmani, O. lathericius and O. badius; Paraneothermes spp., forexample P. simplicicornis; Pseudacanthotermes spp., for example P.militaris and P. spiniger; Reticulitermes spp., for example R. flavipes,R. virginicus, R. tibialis, R. humilis, R. santonensis and R. hesperus;Coptotermes spp., for example C. formosanus and C. crassus; Zootermopsisspp., for example Z. angusticollis and Z nevadensis; Incisitermes(Kalotermes) spp., for example I. minor; Marginitermes spp., for exampleM. hubbardi; Prorhinotermes spp., for example P. simplex; Termes spp.,for example T. fatalis; Trinervitermes spp., for example T. trinervius;very especially Odontotermes smeathmani, Trinervitermes trinervius andAmitermes evuncifer.

Preferred is a method according to the instant invention for controllingsubterranean termites, especially of Reticulitermes, Coptotermes andZootermopsis; very especially Reticulitermes. Also preferred is a methodaccording to the instant invention for controlling drywood termites,especially Cryptotermes, Incisitermes and Neotermes. Another preferredembodiment of the instant invention is a method for controllingpowderpost (furniture) termites, especially Cryptotermes.

On the one hand, preferred is the control of structural termites whichdamage buildings. On the other hand, also the control of agriculturalspecies is preferred. Agricultural termite species are those termiteswhich damage crops.

Further pests that cause damage to wood by feeding on wood, living onwood or reproducing on wood are understood to include, for example,wood-boring insects such as representatives of the family Lyctidae, ofthe family Apidae, for example Xylocopa virginica, and of the familyAnobiidae, e.g. Anobium punctatum.

Termites can cause considerable damage to buildings, crops and storedgoods especially in geographical latitudes between 42° N and 42° S. Twokinds of termites are in principle differentiated:

Subterranean termites which are the most widespread, require warm airand a moist environment. In order that such termites always have accessto the necessary moisture, they must have a direct connection to moistsoil. Damage by termites that are active underground is almost alwaysassociated with damage to wood.

Termites whose habitat is on dry wood, although less common, represent amajor problem because they do not require contact with moist ground.They gain access to buildings under roof shingles and through cracks andair vents. Others are also brought into homes by way of furniture thatis already infested. Pretreating wood is considered the most effectivemethod of controlling such termites. Because the damage caused bytermites living on dry wood is produced more slowly than that caused bytermites living in a moist environment, damage by the former is foundespecially in old buildings.

Damage by termites living underground in a moist environment can beprevented especially by applying insecticidally active substances to thetermites or to their habitat. Such compounds are conventionally usedespecially by application to the ground around the buildings, crops andstored goods.

The currently available compositions for controlling termites are notsatisfactory in all respects because comparatively large areas aroundbuilding structures, or the buildings themselves, usually have to betreated with large amounts of insecticide. That can lead to subsequentproblems especially in houses, more especially when persistentpesticides are used. There therefore exists a further need for improvedsolutions, especially using an active ingredient that can be used inespecially small amounts and that is of low volatility.

The invention accordingly relates also to pesticidal compositionscomprising thiamethoxam, such as emulsifiable concentrates, suspensionconcentrates, directly sprayable or dilutable solutions, coatablepastes, dilute emulsions, wettable powders, soluble powders, dispersiblepowders, wettable powders, dusts, granules, pellets, aerosols orencapsulations in polymer substances, the type of formulation beingchosen in accordance with the intended objectives and prevailingcircumstances. Such compositions used against wood pests are, forexample, of the same kind as those described in EP-A-736 252.

Thiamethoxam is used in those compositions in pure form, for example ina specific particle size, or preferably together with—at least—one ofthe adjuvants or carriers customary in formulation technology.

Formulation adjuvants used are, for example, solid carriers, solvents,stabilisers, “slow release” adjuvants, colorants and optionallysurface-active substances (surfactants). Suitable carriers and adjuvantsinclude any substances customarily used in plant protectioncompositions. Suitable adjuvants, such as solvents, solid carriers,surface-active compounds, non-ionic surfactants, cationic surfactants,anionic surfactants and other adjuvants in the compositions usedaccording to the invention include, for example, the same substances asthose described in EP-A-736 252, page 7, line 51 to page 8, line 39,which are included in the present application by reference.

The compositions to be used according to the invention for controllingwood pests are prepared in known manner, in the absence of adjuvants,for example by grinding and/or sieving, for example to a specificparticle size, or compressing the active ingredient, or in the presenceof at least one adjuvant, for example by intimately mixing and/orgrinding the active ingredient with the adjuvant(s). The inventionrelates also to those processes for the preparation of the compositionsaccording to the invention and to the use of thiamethoxam in thepreparation of those compositions.

The compositions usually comprise 0.1 to 99%, especially 0.1 to 95%, ofactive ingredient, and 1 to 99.9%, especially 5 to 99.9%, of—atleast—one solid or liquid adjuvant, it generally being possible for 0 to25%, especially 0.1 to 20%, of the compositions to be surfactants (ineach case percentages are by weight). Whereas commercial products willpreferably be formulated as concentrates, the end user will also oftenemploy dilute formulations which have substantially lower activeingredient concentrations. Preferred formulations have especially thefollowing composition (%=percent by weight):

Emulsifiable concentrates: thiamethoxam: 1 to 90%, preferably 5 to 20%surfactant: 1 to 30%, preferably 10 to 20% solvent: 5 to 98%, preferably70 to 85% Dusts: thiamethoxam: 0.1 to 10%, preferably 0.1 to 1% solidcarrier: 99.9 to 90%, preferably 99.9 to 99% Suspension concentrates:thiamethoxam: 5 to 75%, preferably 10 to 50% water: 94 to 24%,preferably 88 to 30% surfactant: 1 to 40%, preferably 2 to 30% Wettablepowders: thiamethoxam: 0.5 to 90%, preferably 1 to 80% surfactant: 0.5to 20%, preferably 1 to 15% solid carrier: 5 to 99%, preferably 15 to98% Granules: thiamethoxam: 0.5 to 30%, preferably 3 to 15% solidcarrier: 99.5 to 70%, preferably 97 to 85%

The activity of the compositions according to the invention can besubstantially broadened and adapted to prevailing circumstances by theaddition of other, for example insecticidal, acaricidal and/orfungicidal, active ingredients. Examples of suitable additionalinsecticidal and acaricidal active ingredients include representativesof the following classes of compounds: organophosphorus compounds,nitrophenols and derivatives, formamidines, nitroenamine derivatives,nitro- and cyano-guanidine derivatives, ureas, benzoylureas, carbamates,pyrethroids, chlorinated hydrocarbons and Bacillus thuringiensispreparations. Especially preferred mixing partners are, for example,azamethiphos; chlorfenvinphos; cypermethrin, cypermethrin high-cis;cyromazine; diafenthiuron; diazinon; dichlorvos; dicrotophos;dicyclanil; fenoxycarb; fluazuron; furathiocarb; isazofos; jodfenphos;kinoprene; lufenuron; methacriphos; methidathion; monocrotophos;phosphamidon; profenofos; diofenolan; a substance obtainable from theBacillus thuringiensis strain GC91 or from NCTC11821; pymetrozine;bromopropylate; methoprene; disulfoton; quinalphos; taufluvalinate;thiocyclam; thiometon; aldicarb; azinphos-methyl; benfuracarb;bifenthrin; buprofezin; carbofuran; dibutylaminothio; cartap;chlorfluazuron; chlorpyrifos; cyfluthrin; lambda-cyhalothrin;alpha-cypermethrin; zeta-cypermethrin; deltamethrin; diflubenzuron;endosulfan; ethiofencarb; fenitrothion; fenobucarb; fenvalerate;formothion; methiocarb; heptenophos; imidacloprid; isoprocarb;methamidophos; methomyl; mevinphos; parathion; parathion-methyl;phosalone; pirimicarb; propoxur; teflubenzuron; terbufos; triazamate;fenobucarb; tebufenozide; fipronil; beta-cyfluthrin; silafluofen;fenpyroximate; pyridaben; fenazaquin; pyriproxyfen; pyrimidifen;nitenpyram; acetamiprid; avermectin B₁ (abamectin); emamectin; spinosad;a plant extract that is active against insects; a preparation comprisingnematodes that are active against insects; a preparation obtainable fromBacillus subtilis; a preparation comprising fungi that are activeagainst insects; a preparation comprising viruses that are activeagainst insects; chlorfenapyr; acephate; acrinathrin; alanycarb;alphamethrin; amitraz; AZ 60541; azinphos A; azinphos M; azocyclotin;bendiocarb; bensultap; beta-cyfluthrin; BPMC; brofenprox; bromophos A;bufencarb; butocarboxim; butylpyridaben; cadusafos; carbaryl;carbophenothion; chloethocarb; chlorethoxyfos; chlormephos;cis-resmethrin; clocythrin; clofentezine; cyanophos; cycloprothrin;cyhexatin; demeton M; demeton S; demeton-S-methyl; dichlofenthion;dicliphos; diethion; dimethoate; dimethylvinphos; dioxathion;edifenphos; esfenvalerate; ethion; ethofenprox; ethoprophos; etrimphos;fenamiphos; fenbutatin oxide; fenothiocarb; fenpropathrin; fenpyrad;fenthion; fluazinam; flucycloxuron; flucythrinate; flufenoxuron;flufenprox; fonophos; fosthiazate; fubfenprox; HCH; hexaflumuron;hexythiazox; iprobenfos; isofenphos; isoxathion; ivermectin; malathion;mecarbam; mesulfenphos; metaldehyde; metolcarb; milbemectin; moxidectin;naled; NC 184; omethoate; oxamyl; oxydemeton M; oxydeprofos; permethrin;phenthoate; phorate; phosmet; phoxim; pirimiphos M; pirimiphos E;promecarb; propaphos; prothiofos; prothoate; pyrachlophos;pyridaphenthion; pyresmethrin; pyrethrum; tebufenozide; salithion;sebufos; sulfotep; sulprofos; tebufenpyrad; tebupirimphos; tefluthrin;temephos; terbam; tetrachlorvinphos; thiacloprid; thiafenox; thiodicarb;thiofanox; thionazin; thuringiensin; tralomethrin; triarthene;triazophos; triazuron; trichlorfon; triflumuron; trimethacarb;vamidothion; xylylcarb; YI 5301/5302; zetamethrin; DPX-MP062-indoxacarb;methoxyfenozide; bifenazate; XMC (3,5-xylyl methylcarbamate) or thefungal pathogen Metarhizium anisopliae; very especially fipronil,abamectin, emamectin, spinosad and lambda-cyhalothrin.

Another embodiment is a method for protecting wood from the attack ofwood-destroying pests.

In an especially preferred embodiment of the invention, a compositioncomprising thiamethoxam is used to control termites and/or otherwood-destroying pests in the ground, by means of which indirectprotection of wood structures, crops and stored goods is achieved.

For that purpose, an amount of thiamethoxam sufficient for controllingthe pests is applied to the ground, preferably at a rate of applicationof from 1 g to 2000 g, especially from 5 to 1000 g, more especially from10 to 500 g, per hectare.

Worker termites have to walk on the ground that has been treated withthe pesticide in order to reach the wood, inevitably taking up some ofthe pesticide in the process and carrying it back into the termite nest,and consequently spreading the active ingredient in the termite nest.

The active ingredient can therefore also be presented in the form ofbait, for example in the form of tablets comprising the activeingredient, e.g. as described in U.S. Pat. No. 5,096,710. Specialpreference is given to application of the composition to materials thatare used by the termites as food and as building materials for thetermite nest. Examples of such materials are cardboard, paper, wood,wood dust, cellulose powder or cotton. Suitable concentrations on suchmaterials are from 0.01 to 10 000 ppm. Such bait is especially effectivewhen pheromones are also employed and wood is used that is alreadyinfested with fungi. Such modes of application are discussed, forexample, in U.S. Pat. No. 5,151,443.

Another especially preferred method of controlling termites is theapplication of the active ingredient in the form of microcapsules. Afurther preferred method is the incorporation of the active ingredientinto the building materials, e.g. insulating foam and fireboard. Anotherpreferred method is the application of the active ingredient via slowrelease polymer matrices.

In the area of wood pest control, the compositions according to theinvention are valuable preventive and/or curative compositions having avery advantageous biocidal spectrum even at low rates of concentration,while being well tolerated by warm-blooded animals, fish and plants. Thecompound or compound mixtures of the invention are effective against allor individual development stages of normally sensitive wood pests, butalso of resistant wood pests, especially termites. The action ofthiamethoxam may manifest itself directly, i.e. in the mortality of thepests, which occurs immediately or only after some time, or indirectly,for example in reduced oviposition and/or hatching rate, good activitycorresponding to a mortality of at least 50 to 60%.

With the compositions according to the invention it is also possible toavoid or reduce damage caused to plants by wood pests, especially tocontrol pests of the said kind on useful plants and ornamentals inagriculture, in horticulture and in forestry, or on parts of suchplants, such as the fruit, bölossom, leaves, stems, tubers or roots,while in some cases parts of the plants that grow later are also stillprotected against those pests. Suitable target crops in the context ofcontrolling the said wood pests include especially cereals, such aswheat, barley, rye, oats, rice, maize, sorghum, millet and manioc; beet,such as sugar beet and fodder beet; fruit, such as pomes, stone fruitand soft fruit, such as apples, pears, plums, peaches, almonds,cherries, or berries, for example strawberries, raspberries andblackberries; leguminous plants, such as beans, lentils, peas andsoybeans; oil plants, such as rape, mustard, poppy, olives, sunflowers,coconut, castor oil plants, cocoa beans and groundnuts; cucurbitaceae,such as marrows, cucumbers and melons; fibre plants, such as cotton,flax, hemp and jute; citrus fruit, such as oranges, lemons, grapefruitand mandarins; vegetables, such as spinach, lettuce, asparagus,cabbages, carrots, onions, tomatoes, potatoes and paprika; lauraceae,such as avocados, cinnamon and camphor; and tobacco, nuts, coffee,aubergines, sugar cane, tea, pepper, vines, hops, bananas, naturalrubber plants, eucalyptus, as well as ornamentals. Especially preferredareas of use are crops of groundnuts, cocoa beans, sugar cane, coconut,rice, cotton, millet, maize, manioc, sorghum and eucalyptus.

Further areas of use according to the invention include the protectionof stored goods and storerooms and raw materials from wood pests.

The Examples that follow serve to illustrate the invention. They do notlimit the invention.

APPLICATION EXAMPLES Example A1

Activity Against Termites

Wood bait is treated with different amounts of thiamethoxam and theinfluence on the hatching rate and survival of termites is tested.Solutions having concentrations of 0 ppm, 0.1 ppm, 100 ppm and 1000 ppmof thiamethoxam in acetone are used. Water is used in the control study.The bait consists of pine wood that has been kept for four months in anatural environment.

The termites are collected in the environment from infested pieces ofwood. For the wood bait study, the wood is held in an oven at 80° C. for48 hours. The dried wood is then weighed and the pieces are placed insolutions of thiamethoxam of the desired concentration for 18 hours. Thepieces of wood are then removed from the solutions, dried in air andre-weighed. In order to determine the activity of the bait againsttermites, the pieces of wood so treated are placed on a thin layer ofuntreated soil in petri dishes.

The termites (50 workers and 2 soldiers) are introduced into each petridish. The dishes are inspected three times a week for 8 weeks. Thedevelopment of the insects, abnormalities and mortality are recorded.After 8 weeks, the blocks of wood are rinsed with water and again driedin an oven at 80° C. for 48 hours. The weight of each piece of wood isthen re-determined. The difference in the weights gives the amount ofwood consumed by the termites.

The compositions according to the invention exhibit good activity inthis test.

1. A method of controlling termites, which comprises applying to thetermites or to their habitat a termiticidally effective amount of atermiticidal composition comprising: (a) a termiticidal activeingredient (i) consisting of thiamethoxam, in free form or in the formof an agrochemically acceptable salt, or (ii) consisting ofthiamethoxam, in free form or in agrochemically acceptable salt form andat least one insecticide mixing partner selected from fipronil andlambda-cyhalothrin; and (b) at least one adjuvant.
 2. The methodaccording to claim 1, characterised in that thiamethoxam in free form isused.
 3. The method according to claim 1 wherein thiamethoxam is appliedin the form of microcapsules.
 4. A method of protecting wood from theattack by termites, which comprises applying to the wood to be protectedor to the habitat of the termites a termiticidally effective amount of atermiticidal composition comprising: (a) a termiticidal activeingredient (i) consisting of thiamethoxam, in free form or inagrochemically acceptable salt form, or (ii) consisting of thiamethoxam,in free form or in agrochemically acceptable salt form and at least oneinsecticide mixing partner selected from fipronil andlambda-cyhalothrin; and (b) at least one adjuvant.
 5. The methodaccording to claim 4, characterised in that thiamethoxam in free form isused.
 6. The method according to claim 4 wherein thiamethoxam is appliedin the form of microcapsules.